RFID tag chips and tags with alternative behaviors and methods

ABSTRACT

RFID tags, ICs for RFID tags, and methods are provided. In some embodiments, an RFID tag includes a memory with multiple sections, and a processing block. The processing block may map one of these sections, or another of these sections, for purposes of responding to a first command from an RFID reader. As such, an RFID tag can operate according to the data stored in the section mapped at the time. In some embodiments, a tag can even transition from mapping one of the sections to mapping another of the sections. This can amount to the tag exhibiting alternative behaviors, and permits hiding data on the tag.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of co-pending U.S. Provisionalapplication Ser. No. 12/404,934 filed on Mar. 16, 2009, the disclosureof which is hereby incorporated by reference for all purposes.

This application is a continuation-in-part of co-pending U.S. patentapplication Ser. No. 11/872,774, filed Oct. 16, 2007, entitled “RFID TAGCHIPS AND TAGS WITH ALTERNATIVE MEMORY LOCK BITS AND METHODS”, commonlyassigned herewith.

BACKGROUND

Radio Frequency IDentification (RFID) systems typically include RFIDtags and RFID readers. RFID readers are also known as RFIDreader/writers or RFID interrogators. RFID systems can be used in manyways for locating and identifying objects to which the tags areattached. RFID systems are particularly useful in product-related andservice-related industries for tracking objects being processed,inventoried, or handled. In such cases, an RFID tag is usually attachedto an individual item, or to its package.

In principle, RFID techniques entail using an RFID reader to interrogateone or more RFID tags. The reader transmitting a Radio Frequency (RF)wave performs the interrogation. The RF wave is typicallyelectromagnetic, at least in the far field. The RF wave can also bepredominantly electric or magnetic in the near field. The RF wave mayencode one or more commands that instruct the tags to perform one ormore actions.

A tag that senses the interrogating RF wave responds by transmittingback another RF wave. The tag generates the transmitted back RF waveeither originally, or by reflecting back a portion of the interrogatingRF wave in a process known as backscatter. Backscatter may take place ina number of ways.

The reflected-back RF wave may further encode data stored internally inthe tag, such as a number. The response is demodulated and decoded bythe reader, which thereby identifies, counts, or otherwise interactswith the associated item. The decoded data can denote a serial number, aprice, a date, a destination, other attribute(s), any combination ofattributes, and so on. Accordingly, when a reader reads a tag code,information can be learned about the associated item that hosts the tag,and/or about the tag itself.

An RFID tag typically includes an antenna system, a radio section, apower management section, and frequently a logical section, a memory, orboth. In earlier RFID tags, the power management section included anenergy storage device, such as a battery. RFID tags with an energystorage device are known as active or semi-active tags. Advances insemiconductor technology have miniaturized the electronics so much thatan RFID tag can be powered solely by the RF signal it receives. SuchRFID tags are called passive tags.

With RFID tag usage proliferating, tagged items are now becomingcommonplace in the consumer environment. Challenges arise because of theconcern that someone would try to surreptitiously read the RFID tags ofothers.

SUMMARY

The invention improves over the prior art.

Briefly, the present invention provides RFID tags, ICs for RFID tags,and methods. In some embodiments, an RFID tag includes a memory withmultiple sections, and a processing block. The processing block may mapone of these sections, or another of these sections, for purposes ofresponding to a first command from an RFID reader. An RFID tag canoperate according to the data stored in the section mapped at the time.In some embodiments, a tag can even transition from mapping one of thesections to mapping another of the sections.

RFID tags according to embodiments can be used in many applications. Atag operating according to different mapped data can exhibit differentbehaviors, for example exhibiting alternative identities of the tag, orof its host item. Plus, by remapping, a tag can be electronicallyaltered to enhance consumer privacy and protect sensitive data.

These and other features and advantages of the invention will be betterunderstood from the specification of the invention, which includes thefollowing Detailed Description and accompanying Drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The following Detailed Description proceeds with reference to theaccompanying Drawings, in which:

FIG. 1 is a block diagram of components of an RFID system according toembodiments.

FIG. 2 is a diagram showing components of a passive RFID tag, such as atag that can be used in the system of FIG. 1.

FIG. 3 is a conceptual diagram for explaining a half-duplex mode ofcommunication between the components of the RFID system of FIG. 1.

FIG. 4 is a block diagram of an implementation of an electrical circuitformed in an IC of the tag of FIG. 2.

FIG. 5 is a block diagram of components of an electrical circuit formedin a tag IC according to embodiments.

FIG. 6 is a flowchart for illustrating methods for RFID tags and tag ICsaccording to embodiments.

FIG. 7 is a conceptual diagram illustrating that an RFID tag that usesthe components of FIG. 5 can be in one of different behavior states,correspondingly exhibiting alternative behaviors, according toembodiments.

FIG. 8 is a diagram illustrating a tag transitioning from one of thebehavior states of FIG. 7 to the other according to some embodiments.

FIG. 9 is a flowchart for illustrating an operation of the method ofFIG. 6 according to embodiments.

FIG. 10 is a table showing types of tag behaviors that can be differentaccording to embodiments.

FIG. 11 is a detailed tag memory map of a protocol in the prior art.

FIG. 12 is a diagram showing possible protocol states for a tag IC thatcomplies with the protocol of FIG. 11, further illustrating that, incertain states, a command will cause the designated Electronic ProductCode (EPC) field to be backscattered.

FIG. 13 is a diagram showing two alternative mapping designations of asingle sample tag memory, according to embodiments.

FIG. 14A is a sample partial detailed memory map for a tag, whichimplements a first mapping designation according to embodiments, such asthe first mapping designation of FIG. 13.

FIG. 14B is a sample partial detailed alternative memory map for the tagof FIG. 14A, which implements a second mapping designation according toembodiments, such as the second mapping designation of FIG. 13.

FIG. 15 is a diagram showing an embodiment of a state machine of a tagprocessing block that is capable of exhibiting alternative behaviorsaccording to embodiments.

FIG. 16 is a diagram showing another embodiment of a state machine of atag processing block that is capable of exhibiting alternative behaviorsaccording to embodiments.

FIG. 17 is a conceptual diagram illustrating sample tag behavior statesaccording to embodiments that are advantageous for using with RFID tagsin the supply chain.

FIG. 18 is a diagram showing sample alternative tag memory mappingdesignations for a tag to exhibit the behaviors of FIG. 17 according toembodiments.

FIG. 19 is a conceptual diagram illustrating how the tag can be in oneof different behavior states, which are more than the two behaviorstates of FIG. 17 according to embodiments.

FIG. 20A is a diagram illustrating how, when goods that are movingthrough the supply chain, their RFID tags can be in an easily readablebehavior state such as that of FIG. 17 according to embodiments.

FIG. 20B is a diagram illustrating how, when the goods of FIG. 20A arein a store for sale to consumers, their RFID tags can be in an easilyreadable behavior state, such as the same behavior state of FIG. 20A,according to embodiments.

FIG. 20C is a diagram illustrating how, when the goods for sale in thestore of FIG. 20B are indeed being sold, their RFID tags can be switchedto be in a different behavior state for additional consumer privacyaccording to embodiments.

FIG. 20D is a diagram illustrating how, when the sold goods of FIG. 20Care in the possession of consumers, their RFID tags are in the differentbehavior state with additional consumer privacy according toembodiments.

FIG. 20E is a diagram illustrating how, when an item of FIG. 20D isbeing returned to the store, its RFID tag can be switched to be in a yetdifferent behavior state according to embodiments, such as the easilyreadable state of FIG. 20B.

FIG. 20F is a diagram illustrating how, when the returned item of FIG.20E is being returned through the supply chain, its RFID tag can be inan easily readable state, such as that of FIG. 20B or FIG. 20A.

FIG. 21 is a diagram for illustrating how privacy can be increased bythe invention, for the scenario of FIG. 20D.

FIG. 22 is a diagram for illustrating additional safeguards in changingthe behavior of a tag, such as in FIG. 20E, according to embodiments.

DETAILED DESCRIPTION

The present invention is now described. While it is disclosed in itspreferred form, the specific embodiments of the invention as disclosedherein and illustrated in the drawings are not to be considered in alimiting sense. Rather, these embodiments are provided so that thisdisclosure will be thorough and complete, and will fully convey thescope of the invention to those skilled in the art. Indeed, it should bereadily apparent in view of the present description that the inventionmay be modified in numerous ways. This description is, therefore, not tobe taken in a limiting sense.

As has been mentioned, the present invention provides RFID tags, ICs(also known as chips) for RFID tags, and methods. The invention is nowdescribed in more detail.

FIG. 1 is a diagram of components of a typical RFID system 100,incorporating aspects of the invention. An RFID reader 110 transmits aninterrogating Radio Frequency (RF) wave 112. RFID tag 120 in thevicinity of RFID reader 110 may sense interrogating RF wave 112, andgenerate wave 126 in response. RFID reader 110 senses and interpretswave 126.

Reader 110 and tag 120 exchange data via wave 112 and wave 126. In asession of such an exchange each encodes, modulates, and transmits datato the other, and each receives, demodulates, and decodes data from theother. The data can be modulated onto, and demodulated from, RFwaveforms. The RF waveforms are in a suitable range of frequencies. Suchranges include those near 900 MHz, 2.4 GHz, and so on.

Encoding the data in waveforms can be performed in a number of differentways. For example, protocols are devised to communicate in terms ofsymbols, also called RFID symbols. A symbol for communicating can be adelimiter, a calibration symbol, and so on. Further symbols can beimplemented for ultimately exchanging binary data, such as “0” and “1”,if that is desired. In turn, when the waveforms are processed internallyby reader 110 and tag 120, they can be equivalently considered andtreated as numbers having corresponding values, and so on.

Tag 120 can be a passive tag or an active or semi-active tag, i.e.,having its own power source. Where tag 120 is a passive tag, it ispowered from wave 112.

FIG. 2 is a diagram of an RFID tag 220, which can be the same as tag 120of FIG. 1. Tag 220 is implemented as a passive tag, meaning it does nothave its own power source. Much of what is described in this document,however, applies also to active tags.

Tag 220 is formed on a substantially planar inlay 222, which can be madein many ways known in the art. Tag 220 includes an electrical circuit,which is preferably implemented in an integrated circuit (IC) 224. IC224 is arranged on inlay 222.

Tag 220 also includes an antenna for exchanging wireless signals withits environment. The antenna is usually flat and attached to inlay 222.IC 224 is electrically coupled to the antenna via suitable antenna ports(not shown in FIG. 2).

The antenna may be made in a number of ways, as is well known in theart. In the example of FIG. 2, the antenna is made from two distinctantenna segments 227, which are shown here forming a dipole. Many otherembodiments are possible, using any number of antenna segments.

In some embodiments, an antenna can be made with even a single segment.Different points of the segment can be coupled to one or more of theantenna ports of IC 224. For example, the antenna can form a singleloop, with its ends coupled to the ports. It should be remembered that,when the single segment has more complex shapes, even a single segmentcould behave like multiple segments, at the frequencies of RFID wirelesscommunication.

In operation, a signal is received by the antenna, and communicated toIC 224. IC 224 both harvests power, and responds if appropriate, basedon the incoming signal and its internal state. In order to respond byreplying, IC 224 modulates the reflectance of the antenna, whichgenerates the backscatter from the wave transmitted by the reader.Coupling together and uncoupling the antenna ports of IC 224 canmodulate the reflectance, as can a variety of other means.

In the embodiment of FIG. 2, antenna segments 227 are separate from IC224. In other embodiments, antenna segments may alternatively be formedon IC 224, and so on.

The components of the RFID system of FIG. 1 may communicate with eachother in any number of modes. One such mode is called full duplex.Another such mode is called half-duplex, and is described below.

FIG. 3 is a conceptual diagram 300 for explaining the half-duplex modeof communication between the components of the RFID system of FIG. 1,especially when tag 120 is implemented as passive tag 220 of FIG. 2. Theexplanation is made with reference to a TIME axis, and also to a humanmetaphor of “talking” and “listening”. The actual technicalimplementations for “talking” and “listening” are now described.

RFID reader 110 and RFID tag 120 talk and listen to each other by takingturns. As seen on axis TIME, when reader 110 talks to tag 120 thecommunication session is designated as “R→T”, and when tag 120 talks toreader 110 the communication session is designated as “T→R”. Along theTIME axis, a sample R→T communication session occurs during a timeinterval 312, and a following sample T→R communication session occursduring a time interval 326. Of course interval 312 is typically of adifferent duration than interval 326—here the durations are shownapproximately equal only for purposes of illustration.

According to blocks 332 and 336, RFID reader 110 talks during interval312, and listens during interval 326. According to blocks 342 and 346,RFID tag 120 listens while reader 110 talks (during interval 312), andtalks while reader 110 listens (during interval 326).

In terms of actual technical behavior, during interval 312, reader 110talks to tag 120 as follows. According to block 352, reader 110transmits wave 112, which was first described in FIG. 1. At the sametime, according to block 362, tag 120 receives wave 112 and processesit, to extract data and so on. Meanwhile, according to block 372, tag120 does not backscatter with its antenna, and according to block 382,reader 110 has no wave to receive from tag 120.

During interval 326, tag 120 talks to reader 110 as follows. Accordingto block 356, reader 110 transmits a Continuous Wave (CW), which can bethought of as a carrier signal that ideally encodes no information. Asdiscussed before, this carrier signal serves both to be harvested by tag120 for its own internal power needs, and also as a wave that tag 120can backscatter. Indeed, during interval 326, according to block 366,tag 120 does not receive a signal for processing. Instead, according toblock 376, tag 120 modulates the CW emitted according to block 356, soas to generate backscatter wave 126. Concurrently, according to block386, reader 110 receives backscatter wave 126 and processes it.

In the above, an RFID reader/interrogator may communicate with one ormore RFID tags in any number of ways. Some such ways are described inprotocols. A protocol is a specification that calls for specific mannersof signaling between the reader and the tags.

One such protocol is called the Specification for RFID AirInterface—EPC™ Radio-Frequency Identity Protocols Class-1 Generation-2UHF RFID Protocol for Communications at 860 MHz-960 MHz, which is alsocolloquially known as “the Gen2 Spec”. The Gen2 Spec has been ratifiedby EPCglobal, which is an organization that maintains a website at:<http://www.epcglobalinc.org/> at the time this document is initiallyfiled with the USPTO. Version 1.1.0 of this protocol is herebyincorporated by reference.

In addition, a protocol can be a variant of a stated specification suchas the Gen2 Spec, for example including fewer or additional commandsthan in the stated specification, and so on. In such instances, somecommands can be the same as those of the stated specification, orequivalent to them. For example, the Query command of the Gen2 Specv.1.1.0, if duly followed by other commands, results in singulating atag from other tags. Further sending an ACK command ordinarily causes asingulated tag to return its Electronic Product Code. Another protocolmay have an equivalent command, i.e. one that will have the same effect.Some protocols, such as the Gen2 Spec, allow adding commands thatimplement new or different functionality. These commands are sometimescalled custom commands.

FIG. 4 is a block diagram of an electrical circuit 424. Circuit 424 maybe formed in an IC of an RFID tag, such as IC 224 of FIG. 2. Circuit 424has a number of main components that are described in this document.Circuit 424 may have a number of additional components from what isshown and described, or different components, depending on the exactimplementation.

Circuit 424 includes at least two antenna connections 432, 433, whichare suitable for coupling to one or more antenna segments (not shown inFIG. 4). Antenna connections 432, 433 may be made in any suitable way,such as using pads and so on. In a number of embodiments more than twoantenna connections are used, especially in embodiments where moreantenna segments are used.

Circuit 424 includes a section 435. Section 435 may be implemented asshown, for example as a group of nodes for proper routing of signals. Insome embodiments, section 435 may be implemented otherwise, for exampleto include a receive/transmit switch that can route a signal, and so on.

Circuit 424 also includes a Power Management Unit (PMU) 441. PMU 441 maybe implemented in any way known in the art, for harvesting raw RF powerreceived via antenna connections 432, 433. In some embodiments, PMU 441includes at least one rectifier, and so on.

In operation, an RF wave received via antenna connections 432, 433 isreceived by PMU 441, which in turn generates power for components ofcircuit 424. This is true for either or both reader-to-tag (R→T) andtag-to-reader (T→R) sessions, whether or not the received RF wave ismodulated.

Circuit 424 additionally includes a demodulator 442. Demodulator 442demodulates an RF signal received via antenna connections 432, 433.Demodulator 442 may be implemented in any way known in the art, forexample including an attenuator stage, an amplifier stage, and so on.

Circuit 424 further includes a processing block 444. Processing block444 receives the demodulated signal from demodulator 442, and mayperform operations. In addition, it may generate an output signal fortransmission.

Processing block 444 may be implemented in any way known in the art. Forexample, processing block 444 may include a number of components, suchas a processor, memory, a decoder, an encoder, and so on.

Circuit 424 additionally includes a modulator 446. Modulator 446modulates an output signal generated by processing block 444. Themodulated signal is transmitted by driving antenna connections 432, 433,and therefore driving the load presented by the coupled antenna segmentor segments. Modulator 446 may be implemented in any way known in theart, for example including a driver stage, amplifier stage, and so on.

In one embodiment, demodulator 442 and modulator 446 may be combined ina single transceiver circuit. In another embodiment, modulator 446 mayinclude a backscatter transmitter or an active transmitter. In yet otherembodiments, demodulator 442 and modulator 446 are part of processingblock 444.

Circuit 424 additionally includes a memory 450, which stores data 460.Memory 450 can be implemented by a single type of memory bits, or bymultiple types. Preferably, memory 450 includes Nonvolatile Memory (NVM)bits, which allow at least some of data 460 to be retained even whencircuit 424 does not have power, as is frequently the case for a passiveRFID tag.

In general, an IC made according to embodiments includes a first set ofmemory bits for storing first data, and a second set of memory bits forstoring second data. These multiple sets of memory bits can beimplemented in any number of ways. In some embodiments, the first andthe second sets of memory bits can be wholly distinct from each other.In other embodiments, the first set of memory bits is a subset or asuperset of the second set of memory bits. In yet other embodiments,they may intersect. An example is now described.

FIG. 5 is a block diagram of components 524 of an electrical circuitformed in a tag IC according to embodiments. It will be recognized thatsome of components 524 correspond to analogous components in circuit424. Components 524 include antenna connections 532, 533, similar toantenna connections 432, 433, for coupling to an antenna. Only twoantenna connections 532, 533 are shown, but more are possible, etc.

Components 524 additionally include a memory 550, analogous to memory450. Memory 550 may include a Memory Section A 551, and a Memory SectionB 558. Memory Section A 551 has a first set of memory bits, and MemorySection B 558 has a second set of memory bits. It should be kept in mindthat, in the embodiment of FIG. 5, Memory Section A 551 is shown aswholly distinct from Memory Section B 558, but that is only in theexample of FIG. 5. While Memory Section A 551 does not itself coincideexactly with Memory Section B 558, the two could have portions thatoverlap, or one could be a subset of the other, as will be recognizedfrom the later examples.

The first set of memory bits in Memory Section A 551 stores Data A 561,and the second set of memory bits in Memory Section B 558 stores Data B568. Again, Data A 561 is shown as wholly distinct from Data B 568, butthat is only in the example of FIG. 5. Some of Data A 561 could beshared with Data B 568, if any of the respective memory bits are shared.And, even if not shared, some of Data A 561 could be identical with someof Data B 568.

Components 524 moreover include a processing block 544 made according toembodiments. Processing block 544 can be coupled to the tag antenna viaantenna connections 532, 533. As such, processing block 544 can receivevia the antenna commands that have been issued by an RFID reader, andcan operate in conformance with these commands, as specified accordingto a communication protocol. Such protocols have been described above.Some of these protocols define distinct called-for protocol states forthe tag, and accordingly for processing block 544.

Often such protocols require a tag to send a specific response to afirst interrogator command, if the tag is in an internal tag protocolstate that is compatible with a certain one of the called-for protocolstates. In some embodiments, processing block 544 can indeed be capableof being in an internal tag protocol state that is compatible with thecertain called-for protocol state. In some embodiments, processing block544 can be capable of implementing the present invention with a singleinternal tag protocol state, which can be compatible by being a statethat backscatters an EPC. In other embodiments, processing block 544 canbe capable of attaining also additional protocol states.Implementation-wise, if there are such additional protocol states,processing block 544 can have a protocol state machine to point to whichinternal tag protocol state the processing block is in. Whereasmicroscopically, processing block 544 can be in one or another internaltag protocol state, macroscopically it can be said that the IC chip orthe whole RFID tag is in this or that protocol state. Although theinternal tag protocol states of processing block 544 can be the same asthe called-for protocol states, this embodiment is preferred but notnecessary for practicing the invention.

Often the protocol requires a tag receiving a first interrogator commandto send a specific code in response, if the tag is in a state compatiblewith a certain one of the called-for protocol states. Processing block544, or its host tag, can start by being in such a compatible state, orit can start from a different state and then transition to thecompatible state. Transitioning can be performed in any number of ways.In some embodiments, transitioning can happen in response to receivingone or more preliminary commands, etc. In fact, a number of protocolsrequire such transitioning, and specify how it is to take place. Oftenthis transitioning is performed as part of the tag becoming singulatedfrom other tags.

If processing block 544 is in a state compatible with the certaincalled-for protocol state, it may be able to send a reply code as thespecific code, in response to the first command. Sending the reply codecan be in conformance with the protocol. A protocol state has beencalled compatible for purposes of this document, in that the reply codeis indeed sent with such conformance, whether it is merely a compatibleprotocol state or the exact protocol state.

Processing block 544 can additionally map either the first set of memorybits that are part of Memory Section A 551 or, alternatively, the secondset of memory bits that are part of Memory Section B 558. If processingblock 544 maps the first set of memory bits in Memory Section A 551,which stores the first data, then the reply code can be a first codethat is derived at least in part from the mapped first data.Alternatively, if processing block 544 maps the second set bits inMemory Section B 558, which stores the second data, then the reply codecan be a second code. The second code, derived at least in part from themapped second data, is often different from the first code.

It will be further understood that, while only two memory sections 551,558 are shown among components 524, the invention is not so limited. Forexample, there could a third memory section, with a third set of memorybits, for storing third data. A processing block according to someembodiments can map the third set of memory bits instead of the first orsecond, such that, if the processing block were to receive the firstinterrogator command while in a state compatible with a certain one ofthe called-for protocol states, the reply code could be a third codederived at least in part from the third data, and different from thefirst code and the second code.

In general, an IC made according to embodiments optionally also includesa behavior indicator. If provided, the behavior indicator may indicatewhich of the first set and the second set of memory bits is being mappedby the processing block. In the example of FIG. 5, components 524additionally include an optional behavior indicator 570. If provided,behavior indicator 570 indicates either the first set of memory bits inMemory Section A 551, or the second set of memory bits in Memory SectionB 558. Accordingly, behavior indicator 570, if provided, furtherindicates either Data A 561, or Data B 568.

A behavior indicator is not required explicitly by the invention. Insome embodiments, the behavior state is indicated instead by thecontext, examples of which will be given later in this document.

If provided, behavior indicator 570 can be implemented in any number ofways. In some embodiments, but not necessarily all, the behaviorindicator is encoded in one or more values stored in respective one ormore memory cells of the IC. This is depicted in FIG. 5 by showingoptional behavior indicator 570 as straddling the boundary of tag memory550. If the behavior indicator is indeed encoded in one or more memoryvalues then these values can even be values of the first data, thesecond data, etc.

The invention also includes methods. Such methods according toembodiments are now described more particularly.

FIG. 6 is flowchart 600 illustrating methods according to embodiments.The methods of flowchart 600 may be practiced by different embodiments,including but not limited to RFID tags, tag IC chips, and processingblocks made according to embodiments, for example of the type describedin this document. In addition to flowchart steps, mapping states arealso depicted. What is described below for processing blocks appliesalso to RFID tags and tag IC chips that include such a processing block.

At optional operation 605, a processing block for an RFID tag ICacquires power. This power acquisition can be performed by rectifyingthe power from a wave of an RFID reader.

At optional next operation 620, there is an adjustment of which memorybits the processing block maps, for purposes of responding to a firstcommand by a reader, in the event that this first command is indeedreceived. Operation 620, to the extent it is performed, will bedescribed later in this document. Whether operation 620 is performed ornot, its outcome is a mapping state 610 or, alternatively, a mappingstate 680, which are further included with flowchart 600. Mapping state610 corresponds to a first set of bits being mapped by the processingblock, such as those bits included in Memory Section A 551 of FIG. 5.Mapping state 680 corresponds to a second set of bits being mapped bythe processing block, such as those bits included in Memory Section B558.

At optional next operation 640, one or more preliminary commands arereceived. These can be per the protocol, for singulating the tag, forperforming other functions, and so on.

At optional next operation 650, the processing block can transition to aprotocol state that is compatible with the certain called-for protocolstate for processing the first command, as per the above. Operation 650can be in response to operation 640, or not. In addition, it should bekept in mind that operation 650 is optional, because the processingblock may start by being in that compatible protocol state.

At next operation 660, the first command is indeed received, accordingto a protocol that the reader is using. Typically such a protocoldefines distinct called-for protocol states for the tag, and furtherrequires the tag to send a specific code in response to the firstcommand, if the tag is in a state compatible with a certain one of thecalled-for protocol states. Examples of the first command includecommands that request the tag's Electronic Product Code (EPC), TagIDentifier (TID), a portion of the User Memory (UM), and so on. Moreexamples are described later in this document. At operation 660, thefirst command is received at sufficient power for the tag to respond. Bysufficient, it is meant that the tag would ordinarily send the specificcode without invoking any error codes of the type used to signifyinsufficient power.

At optional next operation 665, the method inquires which set of bits ismapped by the processing block for responding to the first command. Theanswer can be the indicated mapping state 610, or alternatively theindicated mapping state 680, as per the above. In addition the answercan be derived from the behavior indicator, if provided.

If the answer is mapping state 610, then, at next operation 670, a firstcode is sent back in response to the first command, as the specific coderequested by the first command. The first code is derived at least inpart from the mapped first data, as per mapping state 610.

Alternatively, if the answer is mapping state 680, then, at nextoperation 690, a second code is sent back in response to the firstcommand, as the specific code requested by the first command. The secondcode is derived at least in part from the mapped second data, as permapping state 680.

Regardless of whether method 600 or components 524 are considered, thetag sends back a reply code, which is either the first code or thesecond code depending on whether the tag is in mapping state 610 ormapping state 680. In either case the reply code of the invention is theintended reply to the first command, and not normally an error code forthe first command not being right, or its power not being sufficient torespond, or the like. Some implications are now described in moredetail.

FIG. 7 is a conceptual diagram 700, illustrating the alternative mappingstates 610 and 680. Behavior indicator 570, if provided, accordinglyindicates which one of mapping states 610 and 680 is the answer to theinquiry of operation 665.

In addition, two different behavior states 710, 780 can be consideredfor the processing block, or the tag IC, or for the whole tag. Behaviorstate 710 corresponds to mapping state 610, and is characterized by thereply code being the first code of operation 670. Behavior state 780corresponds to mapping state 680, and is characterized by the reply codebeing the second code of operation 690. Behavior indicator 570, ifprovided, accordingly indicates whether the processing block behavesaccording to the first behavior state 710 or, alternatively, the secondbehavior state 780.

Because the first code is generally different from the second code, theprocessing block, and thus the IC chip, and thus also the whole tag, maybe considered as exhibiting alternative behaviors. These alternativebehaviors can be characterized as the tag, or its IC chip, or itsprocessing block, being in one of behavior states 710, 780. Behaviorstates 710, 780, for purposes of this document, are distinct from theprotocol states.

These alternative behaviors can be used to advantage in tagging schemesfor RFID solutions. In particular, these alternative behaviors mayamount to a single tag appearing to be two or more different tags atdifferent times, depending on whether the reply code is the first codeor the second code. Moreover, in embodiments where the reply code isindeed sent back with complete conformance, the reader that has sent thefirst command may be unable to tell whether the tag is further able tobehave differently, and send a different reply code to the firstcommand. In some embodiments, the existence of an alternative behaviormay be communicated to the reader by encoding in the first code anappropriate message, and so on. In that case, RFID readers andApplication Programming Interfaces can be made for detecting themessage, and so on. In other embodiments, the existence of analternative behavior may not be communicated.

In the above examples, the behaviors are indicated as different only asto which code is sent as the reply code, but the invention is notlimited this way—the behaviors can be further different in additionalways. For example, backscattering while in behavior state 710 can be ata different power level than in behavior state 780, for example bypartially detuning the tag antenna, and so on. Moreover, the first orthe second code can be rendered from data as it is stored in respectivememory fields, or by scrambling the data, encrypting the data, and soon.

In addition, whether backscattering takes place at all can depend onother parameters, like the intensity of the wave of the reader. Forexample, in some embodiments, when in behavior state 710, the reply codeis not sent unless the first command has been received at a power levelhigher than a first level. In other embodiments, when in behavior state780, the reply code is not sent unless the first command has beenreceived at a power level different from the first level. This way, thetwo behaviors can be further differentiated, as per the above.

FIG. 8 is a diagram 800 illustrating a tag transitioning from one of thebehavior states of FIG. 7 to the other, according to some embodiments.Transitioning is indicated by an arrow going from behavior state 710 tobehavior state 780. Behavior indicator 570, if provided, accordingly isswitching from indicating behavior state 710 to indicating behaviorstate 780. As per the above, transitioning can be for the processingblock, or the tag IC, or the whole tag.

The transitioning of FIG. 8 corresponds to the tag changing behavior,which can in some embodiments be tantamount to substituting one tag foranother. This is further advantageous when the tag performs thetransitioning electronically, without the need for physical handling.Electronic transitioning confers benefits when the tag is already on ahost item and thus difficult or costly to access physically forsubstituting with another tag, as is described later in this document.

The transitioning of FIG. 8 can be reversible, or not. In someembodiments, after transitioning, the processing block can no longer mapthe first set of memory bits. In others, after transitioning, theprocessing block is further operable to transition back to mapping thefirst set of memory bits. In this latter case, if the processing blockwere to then receive the first command while in a state compatible witha certain one of the called-for protocol states, it would cause the tagto send in response the first code.

The transitioning of FIG. 8 can be implemented by the processing blocktransitioning from mapping the first set of memory bits to mapping thesecond set of memory bits. This alternative mapping was first hinted atas optional operation 620 in the method of FIG. 6, and is now describedin more detail.

FIG. 9 is a flowchart 920 for illustrating more detailed embodiments ofoperation 620 of FIG. 6. In addition to flowchart steps, the mappingstates 610, 680 are also depicted. Flowchart 920 starts with mappingstate 610.

At a next operation 926, there can be a change as to which bits aremapped for responding to the first command. If so, mapping 680 can bearrived at.

At optional further operation 936, there can be a further change as towhich bits are mapped for responding to the first command. If so,mapping 610 can be returned to.

Flowchart 920 also includes optional operations 924, 934. According tothose, the transitioning of operations 926, 936 takes place only ifrespective conditions A, B are met. As such, the tag behavior can becontrolled, and be switched when a desirable event takes place. Thereare many such possible desirable events. For example, transitioning canbe performed in response to the processing block gaining power afterhaving lost power, or after a certain period of time.

In some embodiments the tag IC can further include a counter, which cancount responsive to events. These events can be any suitable type ofevents, such as number of times the tag was singulated, or other eventsrelated to attempts to use, attempts to match an on-board password, orexpected lifetime of the tag. In such embodiments, transitioning can beperformed in response to the counter having counted to a limit. If thecounts are small, the reply code could be the EPC, whereas if multiplesuccessive inventorying attempts are made, the tag could reply to somewith one identity, and to others with an alternate identify.

Additionally, in some embodiments, the tag IC can further include avolatile memory cell, which can store a value temporarily, and thendiscontinue storing the value. Discontinuing would happen if, forexample, the volatile memory cell discharges. In such embodiments,transitioning can be performed in response to the volatile memory celldiscontinuing storing the value, while the processing block is powered.Under the right conditions, the volatile memory cell can optionally befurther refreshed, etc.

Moreover, in some embodiments, transitioning can be performed inconjunction with otherwise transitioning from one of the tag's protocolstates to another. In other embodiments, transitioning can be performedwithout transitioning from one of the tag's protocol states to another.

Gating events can be used for preventing the inadvertent or unauthorizedswitching of behavior states. For example, in some embodiments, abehavior switch enable command must be received by the tag first, beforethe transitioning can take place, and so on. Such commands can furtherbe validated with passwords, etc. In others, the current behavior statecan be locked.

In a number of embodiments, transitioning is performed in response tothe processing block receiving a behavior change command from the RFIDreader. The behavior change command can be distinct from the firstcommand, or derived from the first command. Additionally, the behaviorchange command may be distinct from, the same as, or derived from thebehavior switch enable command.

If the behavior indicator is implemented, it can change which of thefirst set and the second set of memory bits it indicates, in response tothe behavior change command. Moreover, if the behavior indicator isencoded in one or more values stored in memory cells of the IC, thebehavior change command can cause the behavior indicator to be changedby rewriting the one or more values.

There are many possible embodiments for such a behavior change command.If a tag further operates according to a protocol, the behavior changecommand may be a custom command, preferably defined so as to notcontradict the protocol.

It is desirable to control when the behavior change command willactually cause the tag to transition from one behavior state to theother. Controlling can be performed in a number of ways. For example, insome embodiments, the protocol by which the reader sends the firstcommand defines at least two tag protocol states, and the processingblock is capable of being in either one of these two protocol states. Insome such embodiments, transitioning from one behavior state to anotheris performed only if the processing block is in one of these protocolstates, but not in the other. For example, if the tag adheres to theGen2 Spec v.1.1.0, the tag may only implement the behavior changecommand if it is received while the tag is in the Secured protocolstate, but not in another state or set of states.

Moreover, in some embodiments, transitioning can be conditioned onauthenticating the reader transmitting the behavior change command. Forexample, in some embodiments, a password is stored in the IC, such as intag memory. Then transitioning is performed only if the behavior changecommand meets a preset condition about the password. The password can bederived at least in part from one of the first data and the second data.In some embodiments, the password is a tag access password equivalent tothe access password specified in the Gen2 Spec v.1.1.0. In the aboveexample, if the tag adheres to the Gen2 Spec v.1.1.0, for the tag toreach the Secured protocol state the reader must first send the accesspassword, if the tag's stored access password has a nonzero value. Plus,more than one password can be implemented, for example depending on thedirection of the transition. Moreover, transitioning can be performedonly if the behavior change command is received at a power that exceedsa threshold, etc.

FIG. 10 is a table 1000 showing types of tag behaviors that can bedifferent according to embodiments. Column 1020 shows possible tagbehaviors. Column 1050 indicates how memory sections that implement thepossible behaviors can be typically designated, by various protocols.Here, “EPC” stands for Electronic Product Code, and relates to the hostitem to which an RFID tag is affixed. So, it is about identifying thehost item. “TID” stands for Tag IDentifier, and relates to identifyingthe RFID tag itself. The contents of EPC, TID, and “Other” are definedby tagging schemes, or by different parties, such as those establishingthe protocols, the tag manufacturers, or users.

In table 1000, columns 1010, 1080 indicate the data in each of thedesignated memory sections. The two columns represent alternative dataand corresponding alternative tag behaviors. Mapping selects the data,which thereby controls the behavior accordingly. For each behavior, datacan be selected from either column 1010, or column 1080. In someembodiments, a particular type of data can be used only for a particulartype of behavior (e.g. EPC for reported/written product identity). Inothers, as will be seen below, some types of data may be used in morethan one type of behavior.

FIG. 11 is a detailed tag memory map 1160 of a protocol in the priorart. The protocol in question is the Gen2 Spec v.1.1.0, and map 1160appears in Section 6.3.2.1 as Figure 6.17 of that document. Map 1160shows how compliant RFID tags are to address specific memory sections.The EPC and TID sections may correspond to those introduced in FIG. 10.In addition, the designated Reserved Memory and User Memory maycorrespond to what is shown as “Other” in FIG. 10.

In map 1160, the logical addressing of each of the four shown memorybanks begins at zero (00 h). The Gen2 Spec v.1.1.0 allows the physicalmemory underlying map 1160 to be vendor-specific, meaning that it couldcomprise a single memory element, multiple memory elements, etc. TheGen2 Spec v.1.1.0 merely requires that the tag logically expose map 1160in its interactions with a reader. Gen2 v1.1.0 commands that read orwrite tag memory have a MemBank parameter that selects one of the shownfour banks, and an address parameter to select a particular memorylocation within that bank.

FIG. 12 is a diagram showing the called-for protocol states 1220 for atag IC that complies with the Gen2 Spec v.1.1.0. These can be thecalled-for protocol states when the command is per the Gen2 Specv.1.1.0. These can also be the possible internal protocol states of atag that complies with the Gen2 Spec v.1.1.0.

Of protocol states 1220, Ready, Arbitrate and Reply are related to a tagbeing singulated by an RFID reader from among a population of RFID tags.In a number of prior art tags, a state machine is in one of theseprotocol states at a time. Some of the protocol commands cause the statemachine to switch between protocol states.

As shown in FIG. 12, in some of these protocol states a tag may notreply to a reader with its EPC, but in certain other protocol states itcan. Those protocol states in which it can are Acknowledged, Open, andSecured. In all of them a tag will backscatter its EPC in response to anACK command, which in the above is called the first command. In additionto the EPC, more codes may be backscattered in response to the ACKcommand, as denoted by the “[plus]” in FIG. 12.

FIG. 13 is a diagram showing two alternative mapping designations 1311,1381 of a single sample tag memory 1350, according to embodiments.Designation 1311 corresponds to a behavior state A 1310, whereasdesignation 1381 corresponds to a behavior state B 1380. A behaviorindicator 1370, if provided, can indicate either designation 1311, ordesignation 1381. In some embodiments, a tag can transition among thesedifferent designations.

Memory 1350 has fields 1351, 1352, . . . , 1358 of memory bits. Thesefields of memory bits are shown to be of the same size, but that is onlyas an example, and not as a limitation. Each field 1351, 1352, . . . ,1358 may store data. In this embodiment, some of the stored data is useddifferently in different designations, and therefore causes differenttag behaviors.

In first designation 1311, a section 1372 is designated as “EPC”, whichincludes fields 1352, 1353. In addition, a section 1373 is designated as“TID”, which includes fields 1354, 1355. Moreover, a section 1374 isdesignated as User Memory (“UM”), which includes fields 1356, 1357,1358. In some embodiments, these fields are in conformance with theapplicable sections of FIG. 10.

In second designation 1381, a section 1382 is designated as “EPC”, whichincludes fields 1353, 1354. In addition, a section 1383 is designated as“TID”, which includes only field 1355. No other sections are indicated.Again, these can be in conformance with the applicable sections of FIG.10.

It will be observed the data of field 1353 appears in both designations1311, 1381, and in both as an EPC. Its relative location, however, isdifferent in each of designations 1311, 1381.

It will be further observed the data of field 1354 also appears in bothdesignations 1311, 1381, but it is treated differently. In firstdesignation 1311, the data of field 1354 is part of the TID section1373, whereas in second designation 1381, the data of field 1354 is partof the EPC section 1382.

In FIG. 13, first designation 1311 is intended as a general example, inthat it need not conform to any specification. Moreover, firstdesignation 1311 can be for a memory that is compliant with the Gen2Spec v.1.1.0. For example, field 1351 can be considered as the ReservedMemory of FIG. 11, and so on.

It will be appreciated that a detailed memory map for a tag that canbehave as in FIG. 13 will not be as simple as that of FIG. 11, becausethe tag can expose more than one memory map. Instead, partial memorymaps can be used, one for each behavior. Assuming for the time beingthat the tag can expose two such behaviors, the individual partial mapscan informally be called the first map and the second map, the publicmap and the private map, and so on. But such maps are only partial, inthat neither describes the memory completely by itself. Instead, eachpartial map describes only one of the designations in the memory, andthus characterizes only one of the possible multiple behavior states.

An example is now described of two alternative partial memory maps for asingle tag memory. In this example, the designations are intended towork with commands of the Gen 2 Spec v.1.1.0. In other words, thesedesignations show sections that would be addressed by a compliant RFIDtag upon receiving such commands for responding to them.

FIG. 14A is a sample detailed partial memory map 1412 for a tag. Map1412 can be for implementing a first mapping designation, such as firstmapping designation 1311 of FIG. 13. Map 1412 corresponds to a behaviorstate A 1410, as opposed to a behavior state B 1480. A behaviorindicator 1470, if provided, indicates behavior state A 1410. While notnecessary for practicing the present invention, the logical bitaddressing in map 1412 is compliant with the necessary portions of theGen2 Spec v.1.1.0 in this example. Map 1412 shows fields of bits in therightmost column, also with sample physical addresses—in this case theaddresses of physical memory words.

FIG. 14B is a sample detailed partial memory map 1482 that is analternative to map 1412 for the same tag. Map 1482 can be forimplementing a second mapping designation, such as second mappingdesignation 1381 of FIG. 13. Map 1482 corresponds to behavior state B1480. While not necessary for practicing the present invention, thelogical bit addressing in map 1482 is compliant with the necessaryportions of the Gen2 Spec v.1.1.0 in this example. It will be noted thatmap 1482 provides no User Memory—in other words, it hides User Memory,similarly with how designation 1381 hid fields that designation 1311permitted easy access to.

Attention is now drawn to the fields of memory bits with physicaladdresses 22-24, in both FIG. 14A and FIG. 14B. These bits, when theprocessing block is in behavior state A 1410, have logical addresses inthe TID section, whereas when the processing block is in behavior stateB 1480 they have logical addresses in the EPC section. As such, in someembodiments a different command will read them when the tag is inbehavior state A 1410 versus when it is in behavior state B 1480. Ofcourse, in other embodiments, a common command could read themregardless of whether the tag is in behavior state A 1410 or in behaviorstate B 1480, meaning that the command has a common kernel but differentMembank and address fields in each instance.

Transitioning from mapping the first set of memory bits to mapping thesecond set of memory bits is sometimes called remapping. For example, aprocessing block could remap from the partial map of FIG. 14A to that ofFIG. 14B.

As said, partial detailed maps 1412 and 1482 describe a single memorythat can expose different alternative mappings. Note that in either ofthem, explicit behavior indicator 1470 is optional.

As mentioned above, in some embodiments a behavior indicator isimplemented explicitly. In some of these embodiments, the behaviorindicator is encoded in one or more values stored in respective one ormore memory cells of the IC.

There are a number of ways for a stored behavior indicator to indicatewhich of a tag's partial memory maps the tag is to use. In someembodiments a logical memory address, when combined with the one or morevalues encoding the behavior indicator, may produce a physical addressthat the processing block uses to indicate the first set of memory bits,or alternatively the second set of memory bits. In some embodiments, theone or more values that encode the behavior indicator can be used asinputs to a multiplexer or a lookup table that remaps the logicaladdresses to the first set of memory bits, or alternatively to thesecond set of memory bits. Many other methods are possible, as will beobvious to one of ordinary skill in the art.

A behavior indicator can be explicitly implemented, but an explicitbehavior indicator is not necessary for practicing the invention. Aswill be seen, indicating the behavior can be performed implicitly, usingcomponents that serve other functions.

In a number of embodiments, the processing block is capable oftransitioning between two or more internal tag protocol states. Asmentioned above, the internal tag protocol states can be the same asthose called-for by the protocol under which the first command was sent,or different. If different, at least one can be compatible with thecalled-for state, for responding to the first command.

Moreover, in some embodiments, the processing block can be in at leasttwo distinct internal tag protocol states, each of which is a compatibleversion of a single called-for protocol state. In other words, thecommand could call for the tag to be in a single internal protocolstate, but the tag would actually be in one of two internal states, eachof which is a compatible version of the called-for protocol state. Theprocessing block could map the first set of memory bits while in one ofthese states, and the second set of memory bits while in the otherstate. These two internal states can be otherwise similar, in fact evenidentical for purposes of the protocol. If identical, the RFID readermight not know the difference.

This multiplicity of compatible states can be best described byconsidering the processing block as a state machine that transitionsbetween its possible internal tag protocol states. Each internalprotocol state determines what functions the tag can do, how the tagshould respond to which commands, which behavior the tag exhibits, andso on. In such embodiments, at least two of the possible internal tagprotocol states are compatible with a single called-for protocol state,and are otherwise two different versions of the same possible internalstate, for some purposes of the tag. In other words, if the statemachine is in either one of these two states when the first command isreceived, the tag will send in response a reply code in conformance withthe protocol, the reply codes potentially being different depending onthe memory designations for the two states. Two embodiments are nowdescribed. These embodiments build on the above described protocol ofFIG. 12, but that is only by example and not by limitation.

FIG. 15 is a diagram 1500 showing an embodiment of a state machine 1505of a tag processing block. State machine 1505 can be in any one of theshown internal tag protocol states, which are subdivided into twosubgroups 1510, 1580. It will be recognized that each of subgroups 1510,1580, includes a version, A or B, of the protocol states of FIG. 12. Theprocessing block may map a first set of memory bits while state machine1505 is in a state in subgroup 1510, and a second set of memory bitswhile state machine 1505 is in a state in subgroup 1580. In some of theembodiments the tag can be compliant externally with the whole protocol,when state machine 1505 is in version 1510 or 1580 of the called-forprotocol states.

FIG. 16 is a diagram 1600 showing another embodiment of a state machine1605 of a tag processing block. State machine 1605 can be in any one ofthe shown internal tag protocol states. It will be recognized that someof the states are shown singly, while those that cause the EPC to besent are shown in two alternative versions, namely in subgroups 1610 and1680. The processing block may map the first set of memory bits whilestate machine 1605 is in a state in subgroup 1610, and the second set ofmemory bits while state machine 1605 is in a state in subgroup 1680. Insome of the embodiments the tag can be compliant externally with thewhole protocol when state machine 1605 is in any of the versions (singlyshown or the alternatives) of the called-for protocol states.

In some embodiments, for additional security, it is desirable torestrict when remapping can take place. In some embodiments theprocessing block can remap only while in some of its possible internaltag protocol states. More particularly, it is convenient to think of theinternal tag protocol states possible for the processing block asbelonging in different subsets. Each subset includes a number ofpossible internal tag protocol states, or just one internal tag protocolstate. In some of these embodiments, remapping can be performed if theprocessing block is in one of the internal tag protocol states of asecond subset, but not of a first subset. For example, if the processingblock is capable of the internal protocol states of FIG. 12, it might beable to remap only from the Secured state.

The first and second subgroups of internal protocol states that have todo with when remapping is permitted should not be confused with those ofwhere mapping is merely different, such as in FIG. 15 and FIG. 16. Forexample, in FIG. 15, the states in subgroup 1510 map the first set,while those in subgroup 1580 map the second set. Remapping could happenfrom any state, or be restricted to happen only from state Secured-A orstate Secured-B. Similarly with the example of FIG. 16, remapping can bepermitted only by transitioning to state Secured-A or to stateSecured-B.

In some embodiments, there are additional restrictions, or combinationsof restrictions, for the processing block to even enter that specialinternal protocol tag state or states from which remapping is possible.Such special states were characterized above as being in the secondsubset. For a first example, while some commands may require a minimumpower level to be executed, the processing block may be unable to entera state of the second subset unless it receives power at a higher levelthan the minimum. For a second example, a password can be stored in theIC, and the processing block is capable of entering one of the internaltag protocol states in the second subset only if the behavior changecommand meets a preset condition about the password. An example of that,again, is if remapping is permitted only from the Secured internal tagprotocol state, or a version of that Secured state, in which case thepassword could be the Access password of the Gen2 spec v1.1.0.

Returning to FIG. 13, when there is a transition from first designation1311 to second designation 1381, some data becomes harder to read oreven unreadable with an RFID reader. This hard-to-read data includes allof User Memory 1374, plus the data of bit field 1352. Embodiments usingthis advantage of the invention are now described.

FIG. 17 is a conceptual diagram 1700 illustrating sample tag behaviorstates according to embodiments. Two behavior states 1710, 1780 aredefined. A behavior indicator 1770 may be provided. While in behaviorstate 1710, the tag can be easily readable. This is sometimes referredto as the tag being in its “public” behavior. While in behavior state1780, the tag is less easily readable. This is sometimes referred to asthe tag being in its “obscured/privacy” behavior. It should be notedthat state 1780 can be one behavior state, or more.

The tag can transition between behavior states 1710, 1780 using one ormore behavior change commands. Behavior change commands 1720, alsocalled “privatize” commands, can be used to cause a tag to transitionfrom behavior state 1710 to behavior state 1780. Similarly, behaviorchange commands 1790, also called “publicize” commands, can be used tocause a tag to transition from behavior state 1780 to behavior state1710.

As will be seen, an RFID tag can alternate between these behavior states1710, 1780 for increased consumer privacy. Indeed, items that consumersbuy can be tagged with such RFID tags according to embodiments. When anitem is in the supply chain, its tag can be in behavior state 1710,greatly facilitating its handling, and thus generating cost savings.When the item is sold, its RFID tag can be caused to transition tobehavior state 1780, for increased consumer privacy. In some of theseembodiments, when the item is returned, the RFID tag can be caused totransition back to behavior state 1710, and so on.

In another embodiment, an RFID tag can alternate between behavior states1710, 1780 for the purpose of inhibiting the counterfeiting of genuineitems. When an item is in the supply chain, its tag can be in behaviorstate 1780, thereby obscuring one or more of the tag's memory fieldsfrom counterfeiters. As described above, the counterfeiter can beprevented from transitioning the tag to behavior state 1710 by apassword or other security feature. A counterfeiter, not being able toview the obscured information when the tag is in behavior state 1780,cannot easily clone or duplicate the RFID tag. A legitimate distributor,retailer, or law-enforcement personnel can cause the tag to transitionto behavior state 1710 and observe the obscured information, therebydetermining that the item to which the tag is attached is genuine or afake.

The behavior change commands 1720, 1790 can be implemented in any numberof ways. They can be the same as each other, or different. Or they maybe differentiated by one of their fields, or one of their parameters. Orthey can be a parameter-less command that causes the tag to togglebetween behavior states 1710 and 1780, or the like.

If it is desired to work with a protocol that does not normally includesuch commands, then the behavior change commands 1720, 1790 can becreated as custom commands additional to the protocol. When so doing, itis desirable to take the whole protocol into account, so as to notarrive at an inconsistent scheme. In addition, other commands in theprotocol can be consulted to determine the aspects that need caring for,to avoid such an inconsistency.

More particularly, the behavior change command can be implemented firstby a command code. Its bits can be chosen in view of other commands, fortheir usual lengths and formats, but beyond that, the exact choice of 0sand 1s is merely a design choice. The behavior change command canoptionally also have fields and a payload. One of its bits can be a codefor the behavior indicator, to be written in tag memory.

In addition, a tag can have rules as to when to process the behaviorchange command, and when not to, as already mentioned above. It can alsohave rules as to what to backscatter, if anything, depending on whetherthe behavior change command is implemented successfully, or received butnot implemented, or if the tag is unable to implement the commandbecause of an error condition, and so on. Error conditions can be, forexample, if the behavior change command is received with insufficientpower, or an invalid handle, etc. In addition, these rules can specifywhat happens at different internal tag protocol states, and whetherthere is a transition between them, too.

FIG. 18 is a diagram showing sample alternative mapping designations1811, 1881, 1812 for tag memory 1850 of a tag that can exhibit thebehaviors of FIG. 17 according to embodiments. For purposes of clarity,the sample designations of FIG. 18 are intended for tagging a product ina retail application, although as described above the present inventionis not limited to retail applications. Mapping designations 1811, 1812can be for the easily readable behavior state 1710, for use before anitem is sold and after it is returned. Mapping designation 1881 can befor the privacy/obscured behavior state 1780, for use after an item issold and before it is returned.

Memory 1850 has a field 1858, for writing a code that corresponds to thehost item. In this example, field 1858 stores a code with the value“CEREAL”, such as would be used for a cereal box. In designation 1811,section 1871 is the EPC, which includes field 1858. Accordingly, if thetag is inventoried it will report the contents of section 1871,including field 1858, for pre-sale logistics, handling, and the like.

A privatize command 1820 can transition memory 1850 to designation 1881,for example when the item is sold with the tag still attached. In anadditional field 1857 of memory 1850, sale information can be written,for purposes of facilitating returns, legitimizing the sale, lossprevention, warranty, and the like. In some embodiments the saleinformation can be encrypted. This writing can take place prior to, inconjunction with, or even after the sale; it can also take place inconjunction with the privatize command 1820 being received. Moreover, indesignation 1881, section 1872 is the EPC, which includes field 1857,but not 1858. Accordingly, if the tag is inventoried, it will report thecontents of field 1857, but not those of field 1858, thus enhancingconsumer privacy.

A publicize command 1890 can transition memory 1850 to designation 1812,for example when the item is returned with the tag still on it. In anadditional field 1854 of memory 1850, return information can be written.This writing can take place in conjunction with or after the return; itcan also take place in conjunction with the publicize command 1890 beingreceived. It will be observed that, while designation 1812 provides forthe use of field 1854, it is otherwise the same as designation 1811, forpurposes of what can be read easily. In particular, in designation 1812,section 1871 is again the EPC, which includes again field 1858.Accordingly, if the tag is inventoried, it will report the contents ofsection 1871, including field 1858, for post-return logistics, handling,and the like.

FIG. 19 is a conceptual diagram 1900 illustrating how a tag can be inone of several different behavior states. FIG. 19 shows more than thetwo behavior states of FIG. 17 according to embodiments. Behavior state1910 can be the same as behavior state 1710. Plus, there are threeobscured/privacy behavior states, namely 1982, 1984, 1986. Of those,behavior state 1982 is an obscured/privacy/scrambled behavior state, inthat its code is scrambled, making it harder to read by an unauthorizedreader. Behavior state 1984 is an obscured/privacy quiet behavior state,in that will respond only to a reader whose signal is strong enough. Inthis state 1984 the tag will respond when the reader is nearby, but notwhen the reader is farther away, even though in both cases the readersignal may convey sufficient power for the tag to respond. And a tag inbehavior state 1986 replies with a scrambled code only to a reader whosesignal is strong enough. In some embodiments a tag can even reply frombehavior state 1910 when the tag is nearby the reader and receiving astrong signal, but can automatically transition to one of behaviorstates 1982, 1984, 1986 when the tag is far from the reader andreceiving a weak signal.

Referring to FIGS. 20A-20F, examples are now provided for illustratinguses of the invention in retail applications. Referring first to FIG.20A, three domains are examined, namely domain 2040 of a store, domain2030 of a supply chain that is used for goods to reach the store, anddomain 2050 of a consumer that might purchase the goods from the store.

Referring to FIG. 20A, goods are shown in supply chain domain 2030 asthey are being brought to the store. These goods might be processed indistribution centers then trucked to the store, and so on. Three itemsare shown in this example, namely a loaf of bread 2031, a carton of milk2032, and a box of cereal 2033, tagged respectively with RFID tags 2061,2062, 2063 made according to embodiments.

In this example, each of RFID tags 2061, 2062, 2063 is capable of beingeither in a behavior state 2010, or in a behavior state 2080. Behaviorstate 2010 corresponds to the tag being easily readable, similarly towhat was described above for behavior state 1710. Behavior state 2080corresponds to an obscured/privacy state, similarly to what wasdescribed above for behavior state 1780.

As per FIG. 20A, each of RFID tags 2061, 2062, 2063 is in the easilyreadable behavior state 2010. If interrogated by a reader, tag 2061would respond with a code 2091 for “bread”, tag 2062 would respond witha code 2092 for “milk”, and tag 2063 would respond with a code 2093 for“cereal”. The individual memories of the tags can be as shown bypre-sale designation 1811 of FIG. 18.

In the subsequent drawings, to reduce complexity, the individual goods2031, 2032, 2033, are no longer shown. Only their tags are shown, andare considered attached to the goods.

FIG. 20B illustrates how the goods of FIG. 20A have reached the store,and have been placed for sale at various locations in the store. Thestore also includes a sales counter 2022 with an RFID reader 2024, and areturns counter 2025 with an RFID reader 2027.

Like in FIG. 20A, tags 2061, 2062, 2063, if interrogated by a reader inFIG. 20B, would again respond with respective codes 2091, 2092, 2093 forreadings of “bread”, “milk”, and “cereal” respectively, although otherembodiments are also possible, for example in which the store remaps thecodes or adds store or sale information to the tags prior to sale.

FIG. 20C illustrates how goods with tags 2061, 2062, 2063 are beingpurchased by a consumer (not shown). The goods have been brought tosales counter 2022, and their tags 2061, 2062, 2063 are being read byRFID reader 2024. With RFID tags, checkout can be faster, and often moreaccurate as well.

In FIG. 20C, reader 2024 sends privatize commands 2020. Accordingly eachof tags 2061, 2062, 2063 transitions from behavior state 2010 tobehavior state 2080. Their individual tag memories can now become asshown by designation 1881 of FIG. 18. This memory remapping can increaseconsumer privacy, protect sensitive retailer information, or both, asper the above.

FIG. 20D illustrates how goods with tags 2061, 2062, 2063, after thesale in FIG. 20C, are in consumer domain 2050. A consumer 2052 can carrythe goods on their person 2052, in their car 2054, and take them totheir residence 2056. During this time, tags 2061, 2062, 2063 are in theobscured/privacy behavior state 2080, having transitioned to it as shownin FIG. 20C. This means that, if interrogated by a reader, tags 2061,2062, 2063 might not respond at all, or might respond with limited orscrambled information, depending on the exact implementation of theobscured/privacy behavior state. They might respond only with EPC andsale information 1872 from FIG. 18 at long range, and with more detailedinformation at short range. The variety of options according to thepresent embodiments is designated simplistically by tag 2061 respondingwith a code 2094 for a reading of “XX1”, tag 2062 responding with a code2095 for a reading of “XX2”, and tag 2063 responding with a code 2096for a reading of “XX3”.

These readings “XX1”, “XX2”, “XX3” can be harder to decode than therespective readings of “bread”, “milk”, and “cereal” respectively. Forexample, readings “XX1”, “XX2”, “XX3” can correspond to the saleinformation in field 1857 in FIG. 18. The sale information can beunprotected, but it is still less revealing than the item information.Moreover, this sale information, or other information, can be encryptedby the store, and thus even harder to decode. In other embodiments, thereadings can be all identical, further confounding any unauthorizedefforts to read them. An example is shown in FIG. 21, later in thisdocument.

Not shown in FIG. 20D are possible readers located at the store exits,which in embodiments can read the “XX1”, “XX2”, and “XX3” to determinethe legitimacy of a sale without necessarily knowing that “XX1”corresponds to bread, “XX2” to milk, and “XX3” to cereal. In fact, anexit reader seeing a code that starts with XX might be configured to notsound an alarm, whereas the same reader seeing an un-remapped code“bread” might sound an alarm indicating that the item was being stolen.A person with ordinary skill in the art will recognize that the presentinvention and the embodiments described herein can implement thefunctions of Electronic Article Surveillance (EAS) by appropriate use orabsence of the sale information 1857 in designation 1881 of FIG. 18, foritems passing through a store exit.

FIG. 20E illustrates how one item purchased earlier is now beingreturned to the store. The item is brought to the returns counter 2025,and its RFID tag 2063 is read by RFID reader 2027. Reader 2027 isauthorized for this reading. It might first receive the reading “XX3”,as per the above. In any event, reader 2027 issues a publicize command2090. This causes RFID tag 2063 to transition back to the easilyreadable behavior state 2010. Then the full tag can be read again, as inFIG. 20C, and the consumer can be given their refund.

FIG. 20F illustrates the returned item of FIG. 20E available for sale toanother consumer. Tag 2063 is in the easily readable behavior state2010. If interrogated, it would respond again with code 2093 for“cereal”. Its tag memory can be as shown by designation 1812 of FIG. 18.

As was mentioned above, restrictions can be optionally placed in certainof the operations of the invention for additional security. Some suchrestrictions are to require higher power for some of the more sensitiveoperations. Two more examples are now described.

FIG. 21 illustrates a scenario where an unauthorized reader 2131 mightbe used to surreptitiously read RFID tags. This is the scenario ofprotecting consumer privacy, such as shown in FIG. 20D when the tags arein the consumer domain. Reader 2131 might try to read tag 2063 that isclose, within a radius R1, and tag 2165 that is farther away, outsideradius R1. Accordingly, reader 2131 transmits a command 2125 that isencoded in an RF wave.

Tag 2063 perceives the wave as having a large intensity 2133, becausethe reader is close, within a radius R1. Accordingly, depending onembodiments, tag 2063 may respond with obscured reading “XX3”, or with“bread”, because a nearby reader close to the consumer is presumed to belegitimate.

Tag 2165 perceives the wave as having a low intensity 2135, because thereader is far, outside radius R1. While tag 2165 is capable ofresponding, depending on embodiments, it may not do so, or it mayrespond with an obscured reading, because it is in its obscured/privacystate.

FIG. 22 illustrates a scenario where a behavior change command is beingissued. This is what can take place at a returns counter 2025 of FIG.20E, or a sales counter 2022 of FIG. 20C. Reader 2027 will issue acommand 2222, which can reach tags 2063 and 2265. Command 2222 isencoded in an RF wave.

Tag 2063 perceives the wave as having a large intensity 2233, becausethe reader is close, within a radius R2. Accordingly, tag 2063 switchesits behavior state.

Tag 2265 perceives the wave as having a low intensity 2235, because thereader is far, outside radius R2. While tag 2265 is capable of switchingits behavior state, it does not do so, thereby preventing tag 2265 fromexposing its sensitive or hidden information. As described previously,tag 2265, detecting the low intensity wave 2235, could simply choose notto implement the behavior change command, or it could choose not toenter the internal protocol state where the behavior change command isallowed and thereby prevent implementing the behavior change command.Reader 2027 would have to be brought closer, where the consumer couldpresumably clearly see it, in order for tag 2265 to receive wave 2222with sufficient intensity for tag 2265 to change its behavior state.

It will be recognized that the invention permits storing information ina tag such that this information is readable only when the tag is incertain behavior states. Sensitive information can thus be stored, suchas warranty information or passwords, while at the same time otherinformation can be exposed in place of the sensitive information.Storing can be in different places of the memory, so as to be very hardfor an unauthorized person to read. A tag can travel, for examplethrough a portion of the supply chain, while not revealing the sensitiveinformation. There are a number of such entities that can use thisfeature. For example, a legitimate manufacturer may be concerned abouttheir goods being counterfeited, or a tag manufacturer may be concernedabout their tags being counterfeited, etc.

Numerous details have been set forth in this description, which is to betaken as a whole, to provide a more thorough understanding of theinvention. In other instances, well-known features have not beendescribed in detail, so as to not obscure unnecessarily the invention.

The invention includes combinations and subcombinations of the variouselements, features, functions and/or properties disclosed herein. Thefollowing claims define certain combinations and subcombinations, whichare regarded as novel and non-obvious. Additional claims for othercombinations and subcombinations of features, functions, elements and/orproperties may be presented in this or a related document.

What is claimed is:
 1. A Radio Frequency Identification (RFID) tagintegrated circuit (IC) comprising: a memory storing an identifier; anda processing block configurable to: operate in a first behavior state;in response to receiving a first behavior-change command with a powerlevel exceeding a threshold, transition from the first behavior state toa second behavior state, and not transition if the power level does notexceed the threshold; and when operating in the second behavior state beconfigurable to subsequently transition back to the first behaviorstate; wherein the first behavior state is one of a public behaviorstate exposing only a portion of the identifier and a private behaviorstate exposing the entire identifier; and the second behavior state isthe other one of the public behavior state exposing only a portion ofthe identifier and the private behavior state exposing the entireidentifier.
 2. The RFID tag IC of claim 1, wherein the processing blockis further configured to transition from the second behavior state backto the first behavior state upon receiving a second behavior-changecommand.
 3. The RFID tag IC of claim 1, wherein the processing block isfurther configured to modify the threshold in response to receiving afirst command.
 4. The RFID tag IC of claim 1, wherein the processingblock is further configured to temporarily transition from the firstbehavior state to the second behavior state, and to transition back uponlosing power.
 5. The RFID tag IC of claim 1, wherein the processingblock is further configured to only transition from the first behaviorstate to the second behavior state if the first behavior-change commandis received from an authorized reader.
 6. The RFID tag IC of claim 1,wherein the processing block is further configured to only transitionfrom the first behavior state to the second behavior state if the firstbehavior-change command meets a preset condition about a password. 7.The RFID tag IC of claim 1, wherein the processing block is furtherconfigured to only transition from the first behavior state to thesecond behavior state if the first behavior-change command is receivedin a secured protocol state.
 8. The RFID tag IC of claim 7, wherein theprocessing block is further configured to reach the secured protocolstate in response to meeting a preset condition about a password.
 9. TheRFID tag IC of claim 1, wherein the processing block is furtherconfigured to receive at least a portion of its operating power from abattery.
 10. The RFID tag IC of claim 1, wherein the processing block isfurther configured to, in response to receiving the firstbehavior-change command, at least one of: report its current behaviorstate; expose a selected portion of the memory; and revert back to theother behavior state upon losing power.
 11. The RFID tag IC of claim 1,further comprising a behavior indicator.
 12. The RFID tag IC of claim11, wherein the behavior indicator indicates which of the portion of theidentifier and the entire identifier is mapped by the processing block.13. The RFID tag IC of claim 1, further electrically coupled to a dipoleantenna.
 14. A Radio Frequency Identification (RFID) tag integratedcircuit (IC) comprising: a memory storing an identifier; and aprocessing block configurable to: operate in a first behavior state; inresponse to receiving a first behavior-change command that meets apreset condition about a password, transition from the first behaviorstate to a second behavior state, and not transition if the firstbehavior-change command does not meet the preset condition about thepassword; and when operating in the second behavior state beconfigurable to subsequently transition back to the first behaviorstate; wherein the first behavior state is one of a public behaviorstate exposing only a portion of the identifier and a private behaviorstate exposing the entire identifier; and the second behavior state isthe other one of the public behavior state exposing only a portion ofthe identifier and the private behavior state exposing the entireidentifier.
 15. The RFID tag IC of claim 14, wherein the processingblock is further configured to transition from the second behavior stateback to the first behavior state upon receiving a second behavior-changecommand.
 16. The RFID tag IC of claim 14, wherein the processing blockis further configured to only transition from the first behavior stateto the second behavior state if the first behavior-change command isreceived in a secured protocol state.
 17. The RFID tag IC of claim 16,wherein the processing block is further configured to reach the securedprotocol state in response to receiving the password.
 18. The RFID tagIC of claim 14, wherein the processing block is further configured totemporarily transition from the first behavior state to the secondbehavior state, and to transition back upon losing power.
 19. The RFIDtag IC of claim 14, wherein the processing block is further configuredto only transition from the first behavior state to the second behaviorstate if the first behavior-change command is received from anauthorized reader.
 20. The RFID tag IC of claim 14, wherein theprocessing block is further configured to receive at least a portion ofits operating power from a battery.
 21. The RFID tag IC of claim 14,wherein the processing block is further configured to, in response toreceiving the first behavior-change command, at least one of: report itscurrent behavior state; expose a selected portion of the memory; andrevert back to the other behavior state upon losing power.
 22. The RFIDtag IC of claim 14, further comprising a behavior indicator.
 23. TheRFID tag IC of claim 22, wherein the behavior indicator indicates whichof the portion of the identifier and the entire identifier is mapped bythe processing block.
 24. The RFID tag IC of claim 14, furtherelectrically coupled to a dipole antenna.
 25. A method for a RadioFrequency Identification (RFID) tag integrated circuit (IC) comprising:operating in a first behavior state; in response to receiving a firstbehavior-change command with a power level exceeding a threshold,transitioning from the first behavior state to a second behavior state,and not transitioning if the power level does not exceed the threshold;and when operating in the second behavior state, subsequentlytransitioning back to the first behavior state; wherein the firstbehavior state is one of a public behavior state exposing only a portionof a tag identifier and a private behavior state exposing the entire tagidentifier; and the second behavior state is the other one of the publicbehavior state exposing only a portion of the tag identifier and theprivate behavior state exposing the entire tag identifier.
 26. Themethod of claim 25, further comprising transitioning from the secondbehavior state to the first behavior state upon receiving a secondbehavior-change command.
 27. The method of claim 25, further comprisingmodifying the threshold in response to receiving a first command. 28.The method of claim 25, further comprising temporarily transitioningfrom the first behavior state to the second behavior state, andtransitioning back upon losing power.
 29. The method of claim 25,further comprising only transitioning from the first behavior state tothe second behavior state if the first behavior-change command isreceived from an authorized reader.
 30. The method of claim 25, furthercomprising only transitioning from the first behavior state to thesecond behavior state if the first behavior-change command meets apreset condition about a password.
 31. The method of claim 25, furthercomprising only transitioning from the first behavior state to thesecond behavior state if the first behavior-change command is receivedin a secured protocol state.
 32. The method of claim 31, furthercomprising reaching the secured protocol state in response to meeting apreset condition about a password.
 33. The method of claim 25, furthercomprising receiving at least a portion of an operating power from abattery.
 34. The method of claim 25, further comprising, in response toreceiving the first behavior-change command, at least one of: reportinga current behavior state; exposing a selected portion of the memory; andreverting back to another behavior state upon losing power.
 35. Themethod of claim 25, further comprising a behavior indicator indicatingwhich of the portion of the identifier and the entire identifier ismapped by the processing block.
 36. The method of claim 25, furthercomprising electrically coupling to a dipole antenna.